A leakproof seal secondary cell containing alkaline electrolytes was developed by bonding an alkali-resistant elastomer, such as neoprene, to metal contact surfaces. Test results of several different elastomers strongly indicate the feasibility of this sealing method

Sherfey, J. M.

English

NASA Technical Reports Server

August 1964
	 Brief 64-10113 
NASA TECH BRIEF 
This NASA Tech Brief is issued by the Technology Utilization Division to acquaint 
industry with the technical content of an innovation derived from the space program. 
•::i:	
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Elastomers Bonded to Metal Surfaces Seal Electrochemical Cells 
Tab Connection to Electrode 
The problem: Leakproof sealing of secondary cells 
containing alkaline electrolytes. Seals depending on 
the use of ceramics or elastomers held in compres-
sion between the metal lids and terminals of the 
secondary cells are subject to leakage on aging. 
Ceramic seals may deteriorate as the result of electro-
lytic action; elastomeric seals tend to leak because of 
compressive set. 
The solution: A seal formed by bonding an alkali-
resistant elastomer, e.g., neoprene, to the metal lid 
and other metal contact surfaces. 
How it's done: The metal parts are thoroughly 
cleaned to remove grease and other surface contam-
inants. All surfaces to be bonded on the clean metal 
and elastomer are coated with a solution of the same 
elastomeric material,which serves as the bonding agent. 
The coated parts are then placed under proper venti-
lation until the solvent has evaporated. After evapora-
tion has been completed, the parts, with an excess of 
the bonding agent on the surfaces to be sealed, are
Bonded Elastomer Seal 
assembled in a suitable jig. This assembly is then 
placed in a press that forces the parts into their 
correct relative positions and extrudes the excess 
bonding agent. The assembly is kept in the press and 
heated at a fixed temperature for a sufficient time to 
allow the bonding agent to cure. On completion of this 
process, the bonded assembly is taken from the press 
and all extruded material is removed. 
Notes: 
1. The results of accelerated tests with several dif-
ferent elastomers strongly indicate the feasibility 
of this sealing method. 
2. If loss of oxygen or hydrogen by diffusion through 
the seal becomes a problem, a diffusion barrier 
(e.g., a perfluorinated hydrocarbon polymer) can 
be added. 
3. A threaded terminal would make it possible to use 
a nut and an insulating washer to provide addi-
tional support for the seal. If bonded in place, the 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19640000031 2020-03-11T17:06:23+00:00Z
washer could also serve as a diffusion barrier. 
Electrical connections to threaded terminals could 
be made mechanically instead of by soldering, 
which might cause thermal deterioration of the 
elastomer. 
4. For further information about this invention 
inquiries may be directed to: 
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland, 20771 
Reference: B64-101 13
Patent status: NASA encourages the immediate 
commercial use of this invention. Inquiries about 
obtaining rights for its commercial use may be made 
to NASA Headquarters, Washington, D.C., 20546. 
Source: Joseph M. Sherfey 
(GSFC-l68) 
Brief 64-10113


Elastomers bonded to metal surfaces seal electrochemical cells

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